title: Arf6 coordinates actin assembly through the WAVE complex, a mechanism usurped by Salmonella to invade host cells.
abstract: ADP ribosylation factor (Arf) 6 anchors to the plasma membrane, where it coordinates membrane trafficking and cytoskeleton remodelling, but how it assembles actin filaments is unknown. By reconstituting membrane-associated actin assembly mediated by the WASP family veroprolin homolog (WAVE) regulatory complex (WRC), we recapitulated an Arf6-driven actin polymerization pathway. We show that Arf6 is divergent from other Arf members, as it was incapable of directly recruiting WRC. We demonstrate that Arf6 triggers actin assembly at the membrane indirectly by recruiting the Arf guanine nucleotide exchange factor (GEF) ARNO that activates Arf1 to enable WRC-dependent actin assembly. The pathogen Salmonella usurped Arf6 for host cell invasion by recruiting its canonical GEFs EFA6 and BRAG2. Arf6 and its GEFs facilitated membrane ruffling and pathogen invasion via ARNO, and triggered actin assembly by generating an Arf1-WRC signaling hub at the membrane in vitro and in cells. This study reconstitutes Arf6-dependent actin assembly to reveal a mechanism by which related Arf GTPases orchestrate distinct steps in the WRC cytoskeleton remodelling pathway.
authors.affiliation: Department of Pathology, University of Cambridge, Cambridge CB2 1QP, United Kingdom.
authors.forename: Daniel
authors.initials: D
authors.lastname: Humphreys
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Davidson
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hume
authors.forename: Laura E
authors.initials: LE
authors.lastname: Makin
authors.forename: Vassilis
authors.initials: V
authors.lastname: Koronakis
mesh_terms: D020823:ADP-Ribosylation Factor 1 / Q000235:genetics / Q000378:metabolism; D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000235:genetics / Q000378:metabolism*; D000199:Actins / Q000235:genetics / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D012475:Salmonella / Q000378:metabolism* / Q000472:pathogenicity; D012480:Salmonella Infections / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D015238:Sulfotransferases / Q000235:genetics / Q000378:metabolism
chemical_list: D000089982:ADP-Ribosylation Factor 6; D000199:Actins; C411874:CHST15 protein, human; D020690:GTPase-Activating Proteins; D008562:Membrane Glycoproteins; D046912:Multiprotein Complexes; C102474:cytohesin-2; D015238:Sulfotransferases; D020823:ADP-Ribosylation Factor 1; D020727:ADP-Ribosylation Factors; C000715348:ARF6 protein, human
keywords: Rac1; infection; lamellipodia; nucleation-promoting factor